Some types of big earthquakes create small cliffs or fault scarps ∼1–3 m in height, where sediments can pile up and create deposits we call colluvial wedges. Geologists will look at colluvial wedges and use them to understand how often big earthquakes occur. Here we made a computer simulation to find out if the way we think colluvial wedges form works with physics. We found that it does in theory, but there are conditions in which it may be more complicated than we expected.